Ping! PNG

PNG, which stands for Portable Network Graphics, uses lossless compression,
which means that the image loses no quality. Unlike GIF, PNG is patent-free (not
owned). PNG offers palette-based support, grayscale support up to 16-bit,
truecolor support, alpha channel for transparency, and direct support for gamma
correction and color correction.

Gamma correction allows an image that displays properly on different
platforms without losing brightness or contrast. View an image on a Macintosh
and a PC, and you see a difference. Macs display images darker and PCs display
images lighter. An image created on either platform won't look right on the
other platform or even on its own. Without going into highly technical details,
PNG's storing of gamma information enables the system to use the correct
gamma value, if it has one. Sounds great, but there's a catch: Not all
systems know their own gamma values.

If PNG is so great in that it offers alpha channel (RGBa) where GIF only
offers RGB, why isn't PNG more widely in use? Early browser versions
didn't support PNG and companies behind Web sites didn't want to
desert those using such browsers. Like BETA videotapes, it offers excellent
quality, but hasn't gained the support it needs to succeed. However, that
can change, and it's still possible for PNG to gain respect, but beware: It
is also possible that it may never become widely used.